1. Field of the Invention
The present invention relates to a memory card used as a memory device for a personal computer, a work station, or the like.
2. Description of the Related Art
FIG. 8 is a diagram showing a cross section of a part of a conventional general type memory card.
In a memory card 10, there is provided a printed circuit board 11. Semiconductor memory elements 12 and 13, each of which is, for example, a 16 M-bit EEPROM (electrically erasable programmable ROM) contained in a TSOP (thin small outline package), are provided on both sides of the print substrate on the front and rear sides of the memory card 10, respectively formed are insulation plates 14 and 15, and stainless steel-made design plates 16 and 17. In practice, eight semiconductor memory elements are arranged on each of the front and rear sides of the printed circuit board 11, and therefore there are total of sixteen semiconductor memory elements in the memory card.
In general, the thickness of the print substrate is 0.40 mm, and the thickness of one semiconductor memory is 1.20 mm. Accordingly, the total thickness of one print substrate and two semiconductor memory elements is 2.8 mm. Further, the total thickness of two pairs of the insulation plates and the design plates is 0.5 mm. In total, the thickness of the memory card 10 is 3.3 mm.
The memory capacity of a standard-size memory card is limited by the package size of the TSOP in the horizontal plane direction, and by the thickness of the package of the TSOP in the vertical thickness direction. Hence, as mentioned above, a conventional standard-size memory card can pack only sixteen semiconductor memory elements therein.
Further, such a TSOP has outer leads extending from both sides thereof. In a particular case, as shown in FIG. 9, where semiconductor memory elements 12A and 12B are arranged on the same plane of a print circuit board 11 such that the memory elements are adjacent with each other in the direction perpendicular to the arrangement of the outer leads, and the outer leads of the memory elements which have the same function are connected to each other, it is almost impossible to keep the connection wiring pattern straight. As shown in the figure, the wiring pattern 18 must be bent, and therefore the designing of the wiring pattern is very limited. In addition, when a wiring pattern is formed bent as in the above case, the length of the wiring is inevitably increased, and the lengthy wiring can easily be influenced by noise.